Search

The velvet dogfish (Zameus squamulosus) is a dark, nondescript shark species with a wide distribution along the margins of the Atlantic, Pacific, and Indian ocean basins and at a number [...]

The monarch butterfly (Danaus plexippus) is one of the most recognizable North American insects, well known for an annual migration that spans multiple generations and ranges from Mexico to southern [...]

ABSTRACT The cardid bivalve Acanthocardia tuberculata is harvested in southern Spain and on the Atlantic coast of Morocco for the Spanish canning industry. The reproductive cycle and population structure of [...]

The fitness consequences of a delayed timing of breeding are expected to affect the temporal characteristics of the whole annual breeding system. One major problem in quantifying the fitness relevance of timing is that individual differences between pairs may cause the seasonal trend. Differentials in juvenile survival due to pre-fledging timing decisions often only appear after fledging of the chicks. Therefore, timing decisions in the post-fledging period, i.e., the duration of parental care, might additionally influence juvenile survival. We tested the effects of timing and parental competence on the post-fledging survival of second-brood juvenile Barn Swallows (Hirundo rustica L.) by swapping earlier and later hatching clutches and radio-tracking the juvenile subjects. The mark--recapture models controlled for the effects of duration of post-fledging care and food availability. There was an annually varying negative seasonal trend in offspring survival that was associated with environmental conditions. Directional selection for early breeding occurred in the two years with scarce autumnal food supply. Furthermore, we found strong selection for long post-fledging parental care. The duration of care neither declined seasonally, nor did longer care compensate for the seasonal decline of juvenile survival. Hence, the reproductive output three weeks after fledging was determined by two parental timing decisions: the timing of breeding and the timing of family breakup. We suggest that differential survival of second-brood fledglings in relation to these decisions is an important part of the selective mechanisms shaping the reproductive system of Barn Swallows. Key words: Barn Swallow; family breakup; Hirundo rustica; mark--recapture models; parental care; post-fledging survival; radiotelemetry; selection; timing of reproduction.

Barbary macaques mating patterns and male interest in females is found to vary during the ovarian cycle and males were found to detect and concentrate their reproductive efforts to the fertile phase.

The absence of correlation between dominance status and reproduction success in Barbary macaques is due to presence of multiple females in estrus and multiple sexually mature males during the breeding season.

The interaction between menstrual cycle and circadian rhythms in female rhesus monkeys is studied by measuring body temperature, heart rate and physical activity during phases of the menstrual cycle.

An analysis of prototypes of plasmid suppressor and their activity in the sexual cycle of Neurospora intermedia reveals that plasmid suppression depends on strain-specific interaction rather than exclusively relying on the presence of male strains. Transmission and non-transmission of plasmids in female parent strains correspond to the type of male parent strain used in the test crosses. Segregation of suppressed and expressed phenotypes in octads facilitates a substantial test for the genetic basis of suppression phenomenon.

The longitudinal length of Tetrahymena thermophila can be shortened by mixing the starved cells of complementary mating types of this organism. The shortening of length can be achieved within 10 minutes of mixing. This morphogenetic transformation in preconjugant sexual relationship was termed costimulation-induced rounding, which was the first phenomenon observed in cells during the costimulation period. A new morphogenetic transformation that was induced during the early costimulation period of T. thermophila was also found.